An interesting take and one I used to hold myself. I would possibly counter that human beings, being rational creatures, have the unique ability to recognize rationality rationally. A bit Kantian in nature. We use rationality to assign transcendent value to other rational beings. Given this type of thinking, it is possible that humans can be good out of value logic rather than any personal gain. Respecting beings of value given their intrinsic value and nothing else. However, this explanation maybe insufficient given fallibility and lack of genuine access to eternal agent existence (I think therefore I am). This is not really a refutation but a possible alternative.